The invention relates to the field of training devices and simulators, and, more specifically, to training in the use and wearing of a supplemental air supply apparatus that involves a face mask and an exhaustable air supply.
Emergency situations are best handled by personnel skilled in competent procedures that have been acquired through experience and training. The best insurance is good thorough preparation.
Many emergencies require that the responding personnel be provided breathing apparatus to cope with toxic environments. Fires, chemical leaks, explosive atmospheres and underground operations are obvious critical environments where breathing assistance is needed. In such cases the operator must be confident in the apparatus and his own ability to operate it safely and effectively. Otherwise, his attention to the task at hand will suffer in the emergency.
For perfect realism, the apparatus itself would be used in training. But, inasmuch as operational containers of oxygen and oxygen generating devices are used with oxygen breathing apparatuses, cost becomes a significant factor when operational apparatus is employed for training.
Therefore, simulation is encouraged. Accordingly, the next best thing to the perfect realism of the apparatus itself is the apparatus, slightly modified for training. That is what the present invention provides, with an insignificant loss of realism.
Oxygen breathing apparatuses (OBA's) for the most part are closed loop systems which are not vented except by a relief valve. The oxygen canisters and oxygen generators that are used in the system have a limited reserve of breathable air. When the supply is nearly exhausted, the user must discontinue his task and exit the dangerous environment. Then, he can replace the canister with a fresh one, re-enter the dangerous environment, and resume his task. Important, of course, is that the user must be warned before the supply of oxygen is completely exhausted in order to provide for a period of time to escape. Typically, an alarm triggered by a timer is used to alert the user.
If the user persists at his task after the alarm has sounded to signify that the supply of oxygen is about to be exhausted, he will experience a difficulty in breathing that becomes progressively more severe. Finally, the user will be unable to catch a breath when the oxygen supply has been completely exhausted. The inexperienced user will feel a sense of panic when breathing becomes difficlut. His reaction will accelerate his use of oxygen, further deplete the remaining supply of oxygen, and bring about a feeling that he is suffocating. If the panic is severe enough, the period of time he has to escape the dangerous environment before the oxygen supply is exhausted will be dramatically reduced.
Accordingly, each user should experience the sensation of a decreasing supply of oxygen before he is subjected to the sensation in a dangerous environment. Thorough training, including repeated exposure to the sequence of timed alarm followed by progressive difficulty in breathing, will reduce panic during operational use of the OBA, and condition the user to quickly exit the dangerous environment and replenish his oxygen supply before resuming the task. In addition, the training will prepare the user to complete his task on limited oxygen, such as when life or property can be saved in a short period of additional time.
The prior art includes earlier work by the present inventors, such as the simulated oxygen breathing apparatus (OBA) that is described in U.S. Pat. No. 4,539,986, and the OBA simulator using supplemental oxygen that is described in U.S. Pat. No. 4,471,774. The former utilizes high pressure air bottles mounted within the breathing bags of a modified operational breathing apparatus. Air is supplied to the trainee through a plurality of regulators and valves via an air passage opened by a mechanical actuation linkage. The actuator is part of an dummy canister, and is adapted to simulate the actuation of an operational canister. Breathable air is provided to the trainee until either the bottles are exhausted or the dummy canister is removed from its engagement with the bags. The latter patent discloses an invention that comprises a training canister for use with a personal breathing apparatus wherein the canister supplements filtered air with oxygen supplied by an internal cylinder. The canister is part of an open system, and has an integral filter that communicates outside air to the breathing apparatus. Additionally, it utilizes a miniature high pressure valve to release supplemental oxygen into the system from an oxygen cylinder. The training canister simulates operational equipment in size, shape, intergation to the personal breathing apparatus, and actuation. Breathable air is provided to the trainee only after he has installed the canister and has operated its simulated actuation lever. The simulated actuation lever opens a valve to allow filtered air to enter the system, as well as a valve to allow oxygen into the system from the oxygen cylinder.
The prior art's use of a timer to dispense oxygen is shown by U.S. Pat. No. 4,469,097. Therein is disclosed for the medical field a breathing apparatus comprising a miniature canister of pressurized oxygen that can be clipped to the wearer's shirt to provide repeated short bursts of oxygen through a small tube directly to the user underneath his surgical mask as a way to supplement his breathing. The timer controls the opening and closing of a conventional solenoid valve that is in the tube between the oxygen canister and the surgical mask, to pass the small bursts of oxygen to the wearer.
Other means useful or adaptable to enhance the flow of air to a face mask in unusual circumstances when the primary source of oxygen is insufficient or unavailable, albeit for purposes other than those of the present invention, is shown by U.S. Pat. Nos. 4,606,340, 2,486,427, and 2,872,923. The first patent represents the field of improved anti-suffocation valves, the second represents rebreather valves, and the third represents manually controlled inhalation devices. None include timers or are intended for training.